The present invention relates to an oil pan structure of an engine mounted with an axial line of a cylinder of the engine inclined to the vertical direction, and more particularly to the oil pan structure of the engine mounted with a great inclination angle.
Since a commercial vehicle such as a truck cannot have so large engine compartment as a passenger car does, the commercial vehicle may hold its engine under the floor. In such arrangement, the engine is mounted on the vehicle with an axial line of a cylinder of the engine inclined to the vertical direction (so-called a slant engine). Since the engine is mounted in such a manner, its oil pan, which is located at the lowest position, has a different shape from the usual tray-like structure. Tokukai No. Hei 5-86826, for example, discloses an oil pan, of which cross-section is almost a triangle. The specification discloses the invention of the oil pan structure, which includes two chambers (or compartments) with different oil levels within the oil pan, to store enough amount of oil without making the oil pan much bigger. The invention can prevent an oil pump from sucking air when the oil pump sucks oil since an oil strainer, which is an inlet of the oil pump, is disposed in the chamber with higher oil level.
Other than the above publication, Jitsukou No. Hei 6-39047 discloses an invention to change an oil strainer position for an inclined or slant engine. The invention prevents an oil pump from sucking air with oil when the pump sucks the oil by shifting the oil strainer position. However, the invention does not remove mixed air from the oil.
Registered Utility Model No. 2518683 discloses an oil pan having at lease two partition plates within the oil pan for a slant engine. The invention prevents an oil pump from sucking air with oil when the pump sucks the oil by disposing an oil strainer between the two partition plates which are disposed within the oil pan. However, it does not remove already-mixed air from the oil.
Jitsukai No. Sho 59-107911 discloses a baffle plate, to which weight is secured, disposed in an oil pan body.
Both Tokukai No. Hei 9-72209 and Tokukai No. Hei 9-68024 disclose an auxiliary baffle plate in addition to a main baffle plate. These inventions decrease bubble generation when oil drops on the surface of stored oil and allow an oil pump to suck the stored oil, from which mixed air is removed or decreased.
Although the prior art shows these inventions which achieve individual goals or solve problems, respectively, it does not teach any inventions to decrease amount of the air mixed with the oil during lubrication of a crankshaft or other elements when the oil is stored and ready for being sucked by the oil pump, or prevent the oil pump from sucking air mixed with oil, which is stored in the oil pan, through the oil strainer.
Oil dropped from a cylinder block of an engine is returned back to an oil pan after passing around a crankshaft. Since the crankshaft is not moving while an engine is not operating, oil comes down along the cylinder block wall to a first baffle plate, comes into an oil dropping hole on the first baffle plate, which directs the oil towards a bottom of an oil pan, and is returned to the inside of the oil pan. While the engine is operating, much oil seems to be splashed to the crankshaft and circulated around the crankshaft. The oil finally directed to the bottom of the oil pan contains a lot of air bubbles so that it may cause deterioration of aeration performance (oil property endurance to the aeration). Thus, the object of the present invention is to reduce the aeration (mixed air percentage in the oil).
Therefore, the present invention provides the oil pan structure of the engine to keep two oil levels within a certain difference of two chambers partitioned by a second baffle plate in the oil pan in order to reduce the oil level change by vehicle turn and to reduce the aeration at the same time.
The present invention seeks to achieve the above-mentioned goal and provides the oil pan having a horizontal bottom plate and secured to the engine mounted on the vehicle body such that its cylinder axial line is inclined to the vertical face including the crankshaft axis, comprising: a first baffle plate having a horizontal portion separated with a certain distance from the bottom of the oil pan, the first baffle plate having a first opening directing oil towards the bottom of the oil pan; a second baffle plate disposed vertically between the first baffle plate and the bottom of the oil pan to partition the space into two compartments; and an oil passing passageway disposed in a lower position than the horizontal portion of the first baffle plate so that the oil may pass through the passageway between the two compartments in order to equalize the oil level of each compartment (or chamber).
In accordance with the present invention, the first baffle plate can prevent oil from dropping directly from the cylinder block to the surface of the oil stored in the oil pan so as to reduce generation of air bubbles and it can be possible to accelerate removing mixed air bubbles from the oil in either compartment of the two compartments so as to reduce the aeration.
Since the oil passageway (second opening) equalize oil surface heights in the compartments is formed in a portion near the bottom of the oil pan in the second baffle plate the oil passageway may allow oil having relatively less mixed air bubbles to flow between two compartments so that the aeration is effectively reduced when the oil with less air bubbles flows into the other compartment where an oil pump sucks oil up.
In accordance with the present invention, the oil pan structure further comprises an oil strainer for sucking oil in one of the two compartments and an oil dropping hole (third opening) such that the oil may efficiently be collected and the mixed air bubble may efficiently be removed.